JAV, I haven't seen much... But I like Azumi Kawashima (retired!), Hiyori Shiraishi (hottest body ever!) and Maria Takagi (for being Ayaya lookalike)
I really think some of them are ugly though (Aoi Sora, Nao Oikawa...) so I steer clear of those.
In the thin line between nudity and gravure, there stands Haruka Nanami...
Gravure idols-wise, there're so many I like! Right now I guess I love Meguru Ishii, Mari Morishita and Nao Nagasawa the most, followed closely by Yukie Kawamura, Mayuko Iwasa, Tomomi Kudo, Miwa Ooshiro and Aya Hirayama.
I also like Yui Ichikawa, Yoko Mitsuya, Yuka Hirata, Sayaka Isoyama, Saya Kazuki, Miku Matsumoto, Miho Shiraishi, Mao Miyaji, Kei Matsubara, Kanako Kojima, Haruka Ayase, Fumina Hara, Eri Murakami, Eri Kyokuyama, Azusa Yamamoto, Ayumi Ninomiya, Ayano Yamamoto and Aki Kawamura a lot (it's just hard to leave any of these girls out!!).
Singers who have released bikini pbs -- Yuu Hasebe!!~ , Ayumi Shibata, Rika Ishikawa and Aya Matsuura ~~
Actresses who have released bikini pbs -- Ryoko Kuninaka!!~